# std::flat_multiset<Key,Compare,KeyContainer>::clear

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< cpp‎ | container‎ | flat multiset

void clear() noexcept; |  | (since C++23)

Erases all elements from the container adaptor. After this call, size() returns zero.

Invalidates any references, pointers, and iterators referring to contained elements.

### Parameters

(none)

### Return value

(none)

### Complexity

Linear in the size of the container adaptor, i.e., the number of elements.

### Example

Run this code

    #include <iostream>
    #include <string_view>
    #include <flat_set>

    void print_info(std::string_view rem, const std::flat_multiset<int>& v)
    {
        std::cout << rem << "{ ";
        for (const auto& value : v)
            std::cout << value << ' ';
        std::cout << "}\n";
        std::cout << "Size=" << v.size() << '\n';
    }

    int main()
    {
        std::flat_multiset<int> container{1, 2, 3};
        print_info("Before clear: ", container);
        container.clear();
        print_info("After clear: ", container);
    }

Output:

    Before clear: { 1 2 3 }
    Size=3
    After clear: { }
    Size=0

### See also

erase | erases elements (public member function)

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